The present invention relates to world timepieces, and more particularly to a board for progressively displaying the universal time of every time zone and the time differences between the local time and everywhere in the world so as to facilitate a commercial traveller or a tourist to know the exact time of their destination at a glance and to help a teacher to show the time differences of the world in an astronomical class.
Hundred thousands commercial, trade or sightseeing travellers travelling daily in the world need to know the exact time at the departure and arrival between two terminus of their travelling. Since they understand that being punctual is very important for them, but most of them don't know how to obtain the date and the time different at their destinations. In order to meet the requirement mentioned above, various world timepieces have been disclosed heretofore, wherein the most typical prior art world timepieces are the Zone Time Display Clocks, U.S. Pat. No. 3,186,158 and U.S. Pat. No. 3,940,920, which include a world map on a small panel can selectively show the time differences for number of large cities in the world and which are adaptable to whom he is skillfull to operate it personally. U.S. Pat. No. 4,502,789 and 4,945,521 disclosed a clock and a watch, the former of which disposes a rotatable disk including thereon a world map of polar projection into a circular casing. A series of radially extended longitudes of 15.degree. in interval on the map made in registry with a twenty-four hour scale around the circumference of the casing so that the user can visually obtain the time differences of every time zone upon the rotation of the disk. The later depicts a series of concentrical circles on a stationary dial face in which separately indicates the scales of local hours, minutes, the time defferences of 24 time zones and a selected number of major city names in the world, in addition to a plurality of arms coaxially rotate on a central shaft for respectively pointing the scales. This clock or watch is too small to contain informations enough to satisfy user's requirement, and the users feel difficult to read those invisible informations inversibly. U.S. Pat. No. 4,998,229 and 5,007,033 then disclosed a programmable world timepiece which is made of a calculator and includes a display unit normally displaying local time or selectively showing the present time of main cities in the world by pressing a plurality of selector switches in the lower portion. This calculator type world timepiece can also serve for skillfull personal only. So that the aforediscussed prior art world timepieces are of limited function and can not serve for the popularity of the travellers.
Finally, U.S. Pat. No. 2,299,913 discloses a world clock which is of a time display board on which attaches a transparent world map including 24 time zones thereon and incorporated with a time scale of doubled 12 hours on the top thereof. A plurality of colored incandescent bulbs actuated by a plenty of electronic mechanisms for selectively emanating the lights to imitating day or night on the map. But it could not show the transition of the date. Besides, it's mechanism is too complicated to manufacture. This is the reason why it has not come up to realization. Instead of the above world timepieces, a number of clock are arranged in an alignment on a wall in a lounge of an airport, a passenger terminal of a harbour or of a station hall. Each of these clocks tells the time difference of a major city around the world. This arrangement is quite limited to tell the time differences of few major cities and that they need to be adjusted frequently disregarding of whether or not they are operated by A.C. current, therefore causing inconvenience.